External bone fixation system

ABSTRACT

An external bone fixation system may include a first semi-circular external fixation member, a second semi-circular external fixation member, four ball collet assemblies attached to the second external fixation member, and four shafts. Each shaft may include a first end attached to the first external fixation member and a second end with a stop member, and each of the four shafts extends slidably through an opening in a ball of one of the four ball collet assemblies. The stop member of each second end prevents each second end from passing through the opening in its respective ball. Each shaft also includes a hinge located closer to the first end than to the second end.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation of U.S. patent application Ser. No.15/178,977, filed Jun. 10, 2016, and entitled “External Bone FixationSystem,” the entirety of which is hereby incorporated by reference.

FIELD

The present application is related to medical devices, systems andmethods. More specifically, the present application describes anexternal bone fixation device, system and method.

BACKGROUND

External fixation devices have been commonly used for various treatmentsof bone conditions. Such bone conditions include leg lengthening,osteotomies, arthrodesis, open fracture fixations, compound fracturefixations, and other bone conditions amenable to treatment by use of anexternal fixation assembly. For example, external fixation devices aretypically used in treatment of bones when frequent wound care isnecessary to treat an open wound or a surgical site within an extremity.

Although current external fixation devices are often adequate, manyexternal fixation devices are relatively large, include numerouscomponents, are complicated to use, difficult to adjust, and involvechallenging postoperative care and use. For example, current externalfixation devices involve relatively large and numerous components,creating operative difficulties to the practitioner and postoperativedifficulties to the patient. Many devices, for instance, involve a ringor “halo” member disposed about an affected area to provide support topins for fixating bone matter. Such components, however effective, arerelatively bulky and create difficulty for the physician to insert thepins and for the patient to move independently.

These ring or halo fixation devices are often used, for example, byorthopedic surgeons and podiatrists in the treatment of foot injuriesand maladies. Some injuries or conditions involving the foot or anklerequire that these devices be applied to the bones of the foot (e.g.,calcaneus, tarsals, metatarsals, and phalanges) and the lower leg bones(e.g., tibia and fibula). In such circumstances, pins may be insertedinto both the foot and lower leg bones, in order to secure the fixationdevice. Currently available external bone fixation systems, however,have limited rotational ability for a given pin, which is exacerbated bythe complex and varied placement pins used for different patients withdifferent anatomies and injuries.

Therefore, it would be advantageous to have improved external bonefixation devices, systems and methods. Ideally, an improved externalbone fixation system would be relatively simpler than currentlyavailable systems, for example having fewer components and/or being lessbulky and cumbersome for the physician and the patient. Also ideally,the improved system would allow for easier, simpler and more secureconnections between the external fixation components and one or morebone pins connecting the system to the patient's bone(s), includingimproved rotational ability about the pin(s). At least some of theseobjectives will be addressed by the embodiments described in thisapplication.

DESCRIPTION OF PRIOR ART

One example of a prior art approach is found in U.S. Pat. No. 7,465,303(Riccione et al.). Among other embodiments, Riccione teaches the use ofa plurality of compression nuts, the threads of which are mateable withthe threads of a threaded rod. Riccione further describes one or morecollets, comprising collet sleeves and collet nuts. The one or morecollets are configured to hold a bone pin and form a compression lock inthe apertures, when the collet nuts are tightened against the pinholding elements during use. This patent, however, fails to teachmultiple orientational components, such as a slideable bracket, a colletand/or other components, which may be fixed in location through the useof a single fastener.

Another discussion of a prior art approach may be found in U.S. Pat. No.8,235,994 (Hollawell), which teaches a fixator for use in thereconstruction of acute, chronic and traumatic injuries to the upper andlower extremities. Specifically, Hollawell describes a clamping systemthat allows for the snapping in of pins and rails, and for multi-planarfixation of bones. Hollawell fails to teach, however, the ability toindependently rotate and set a pin within a collet clamp having a fixedlocation. Hollawell also does not describe the ability to have multipleindependently rotatable axes for fixing a pin location, where the systemmay be fixed in location using a single fastener.

DEFINITION OF TERMS

The terms “rod,” “pin” and “nail” are used interchangeably. All threeterms refer to a rigid, elongate component that is inserted into one ormore bones for the purpose of anchoring, stabilizing, repairing, orsupporting the bone(s). The term “rod” usually implies a relativelylarge device, while the term “pin” implies a somewhat smaller device;however, there is no clear boundary between these terms. In addition,the term “rod” (and the terms “rail” and “tube”) is not limited to anyparticular cross-sectional shape, and may in fact be circular, oval,square, rectangular, polygonal or any combination thereof, while stillfalling within the term “rod” as used herein.

As used herein, the term “threaded” indicates that a rod or pin hasscrew-type threads on its external surface; however, a non-threaded rodor pin can have one or more threaded holes passing through it, forfixation screws, so long as the threads are not exposed on the externalsurface. A rod externally threaded along at least a part thereof isgenerally referred to as a screw. The screws maybe threaded at one orboth ends, based on the preferred use of the screw. In some cases,however, non-threaded rods or pins can be used and would still fallwithin the scope of a “threaded engagement” as used herein, especiallywhere the non-threaded pin is attached to another element (e.g., bone,plate, rod, pin) sufficiently to hold the rod to the element.

While the terms “rod,” “pin” and “nail” normally tend to imply that animplant does not have an externally threaded surface, some implantedrods, pins and nails have external threads.

Where alternative meanings are possible, the broadest meaning isintended. All words used in this application are intended to be used inthe normal, customary usage of grammar and the English language.

BRIEF SUMMARY

The embodiments described herein provided improved devices, systems andmethods for external bone fixation. In one aspect, an external bonefixation assembly includes a fracture fusion tube, with a bracketslidably engaged thereon. The assembly further includes a collet clampconnected to the bracket, with a perforated ball rotatably seated withinthe clamp, the ball having an aperture for receiving a bone bintherethrough. The assembly uses a single screw for threadably engagingthe pin collet, the clamp and the bracket, such that the position of theball, bracket, and collet clamp is fixed. Thus, the assembly forexternal bone fixation has multiple axes of rotation for pin placementand setting, where the desired placement may be fixed through the use ofa single screw or similar connector.

The apparatus and method of the present invention generally includes anexternal bone pin assembly that includes a fracture fusion tube forslidably engaging one or more bracket (which may be a clamp or similarstructure). At least one bracket is connected to a collet clamp orsimilar structure which is rotatable around the circumference of thefracture fusion tube. The collet clamp has seated therein a perforatedball for receiving a bone pin therethrough, the ball being rotatablewithin the collet clamp for adjusting the angle of engagement for thebone pin and the bone. The perforated ball is composed of aluminum or asimilar crushable material. The collet clamp and the bracket havealigned apertures, at least one of which is threaded, and a single screwcan be aligned with both apertures, such that tightening a single screwwill secure the bracket and collet clamp into a fixed position, and thecompressive force of the collet clamp from the tightening screw on theperforated ball crimps the ball into a fixed position. Thus, a singlescrew can fix all of the components from a given pin subassemblyextending from the fusion fracture tube. The embodiments herein thusprovide an external bone pin assembly for a simpler assembly, whichprovides greater pin insertion into metatarsals and other bones in thefoot, though alternative embodiments may be applied to other bodilyregions, including the tibia and other bones, using a larger scale butsimilar principle of operation.

In another aspect, an external bone fixation system may include: a firstsemi-circular external fixation member; a second semi-circular externalfixation member; four ball collet assemblies attached to the secondexternal fixation member; and four shafts, each shaft having a first endattached to the first external fixation member and a second endcomprising a stop member. Each of the four shafts extends slidablythrough an opening in a ball of one of the four ball collet assemblies.The stop member of each second end prevents each second end from passingthrough the opening in its respective ball, and each shaft also includesa hinge located closer to the first end than to the second end.

In some embodiments, the first external fixation member and the secondexternal fixation member are horseshoe shaped. In some embodiments, thefirst external fixation member includes four lateral protrusions, eachof which includes a shaft attachment aperture to which one of the firstends of the four shafts is attached. In some embodiments, the firstexternal fixation member includes at least four shaft attachmentapertures equally spaced around the first external fixation member, andeach of the first ends of the shafts is attached to the first externalfixation member via one of the shaft attachment apertures. In someembodiments, the first ends of the shafts are attached to the firstexternal fixation member such that they can spin within, but cannot passvertically through, the shaft attachment apertures. Some embodiments mayinclude more than four attachment apertures, equally spaced along thefirst external member, such that any of the first ends of the shafts maybe detached from a first attachment aperture and moved to a secondattachment aperture. For example, in some embodiments there may be atleast thirty attachment apertures. In some embodiments, the secondexternal fixation member may include at least four collet attachmentapertures, equally spaced around the second external fixation member,and each of the ball collet assemblies is attached to the secondexternal fixation member via one of the collet attachment apertures. Insome embodiments, the second external fixation member may be configuredto slide along the four shafts from a collapsed configuration, in whichthe second external fixation member is located between the hinges of theshafts and the first external fixation member, to a fully extendedconfiguration, in which the second external fixation member contacts thestop members of the four shafts.

Each ball collet assembly may include, in some embodiments: a ball witha central opening and multiple longitudinal slits; an insert withmultiple longitudinal slits and configured to fit over the ball; and aclamp configured to fit over the insert and having only one adjustmentmember to tighten the clamp over the liner and the ball. In someembodiments, the ball may be made of aluminum with a rough surfacecoating, and the insert may be made of PEEK plastic. In one embodiment,the ball of each ball collet assembly may include: at least one fullthickness, full length slit, extending from one end of the ball to anopposite end and from the central opening to an outer surface of theball; and at least one partial slit, which includes a full thicknessportion extending from the central opening to the outer surface, and apartial thickness portion extending only partway from the centralopening to the outer surface. In some embodiments, the full thicknessportion may include two lengths of the partial slit, located at oppositeends of the central opening, and the partial thickness portion may belocated between the two lengths of the full thickness portion. The clampmay include a threaded aperture for accepting a screw to tighten theclamp, and a surface of the threaded aperture may be coated with Teflon.

In some embodiments, the external bone fixation system may also includeat least one bone pin attachment member configured to attach to thefirst external fixation member or the second external fixation memberand to a bone pin. The system may also optionally include a thirdsemi-circular external fixation member, at least four additional ballcollet assemblies, and at least two additional shafts. At least two ofthe additional ball collet assemblies are attached to the third externalfixation member, and at least two of the additional ball colletassemblies are attached to the first external fixation member. Theshafts are slidably coupled between the ball collet assemblies attachedto the third external fixation member and the ball collet assembliesattached to the first external fixation member.

In another aspect, a ball collet assembly for use with an external bonefixation system may include: a ball with a central opening and multiplelongitudinal slits; an insert configured to fit over the ball and havingmultiple longitudinal slits; and a clamp configured to fit over theinsert and having only one adjustment member to tighten the clamp overthe liner and the ball. Again, the ball may be made of aluminum with arough surface coating, and the insert may be made of PEEK plastic, insome embodiments. The ball may include at least one full thickness, fulllength slit, extending from one end of the ball to an opposite end andfrom the central opening to an outer surface of the ball. The ball mayalso optionally include at least one partial slit, which may include afull thickness portion extending from the central opening to the outersurface and a partial thickness portion extending only partway from thecentral opening to the outer surface.

In yet another aspect, a method for attaching an external bone fixationsystem to one or more bones in a lower limb of a patient may involve:positioning a first semi-circular external fixation member over thelower limb at a first location; sliding a second semi-circular externalfixation member along four shafts attached to the first externalfixation member and extending through central openings of four ballcollet assemblies attached to the second external fixation member, toposition the second external fixation member over the lower limb at asecond location; tightening the four ball collet assemblies attached tothe second external fixation member to fix the ball collet assembliesimmovably to the four shafts, thus locking positions of the firstexternal fixation member, the second external fixation member and thefour shafts, relative to one another; and attaching a first bone pinattachment member coupled with the first external fixation member with afirst bone pin extending out of a first bone in the lower limb.

Optionally, the method may also include twisting the first externalfixation member, relative to the second external fixation member, bybending the four shafts at four hinges in the shafts, where each of thefour shafts includes one of the four hinges. The method may alsooptionally include straightening the four shafts via hinges located onthe four shafts, before sliding the second external fixation member froma first position, in which it is located between the four hinges and thefirst external fixation member, to a second position, in which thehinges are located between the first and second external fixationmembers. In some embodiments, sliding the second external fixationmember along the four shafts expands the external bone fixation from acollapsed configuration to an expanded configuration by straighteningthe four shafts at four hinges. In some embodiments, sliding the secondexternal fixation member along the four shafts involves sliding thesecond external fixation member until it contacts four stop membersattached to ends of the four shafts.

The method may also optionally involve attaching a second bone pinattachment member coupled with the first external fixation member with asecond bone pin extending out of the first bone or a second bone in thelower limb. Optionally, the method may also involve attaching a secondbone pin attachment member coupled with the second external fixationmember with a second bone pin extending out of the first bone or asecond bone in the lower limb. In some embodiments, tightening each ofthe four ball collet assemblies over each of the four shafts may involvetightening only one screw of each of the four ball collet assemblies.

These and other aspects and embodiments are described in greater detailbelow, in reference to the attached drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an external bone fixation rail system,applied to metatarsal bones, according to one embodiment;

FIGS. 2A and 2B are top perspective and side views, respectively, of aball of a ball collet assembly, which is part of the external bonefixation rail system of FIG. 1, according to one embodiment;

FIG. 3 is an end-on view of a ball and an insert/sleeve of a ball colletassembly, which is part of the external bone fixation rail system ofFIG. 1, according to one embodiment;

FIG. 4 is an end-on view of a bracket and ball collet assembly engagedwith a single fastener, which is part of the external bone fixation railsystem of FIG. 1, according to one embodiment;

FIGS. 5A and 5B are side perspective views of a bracket and a colletclamp with insert, respectively, which are part of the external bonefixation rail system of FIG. 1, according to one embodiment;

FIGS. 6A-6D are perspective views of another embodiment of an externalbone fixation system, in which external fixation members partiallyencircle a patient's limb, according to one embodiment;

FIG. 7 is a perspective view, with a portion of the figure exploded, ofa ball collet assembly, which is part of the external bone fixation railsystem of FIGS. 6A-6D, according to one embodiment;

FIG. 8 is a perspective view of a patient's limb, with the external bonefixation system of FIGS. 6A-6D in position and coupled with anadditional expansion system, according to one embodiment; and

FIG. 9 is a perspective view of another embodiment of an external bonefixation system, which may in some embodiments be added to anotherfixation system, such as the system of FIGS. 6A-6D.

DETAILED DESCRIPTION

Set forth below is a description of various embodiments of devices,systems and methods for external bone fixation. Future and presentalternatives and modifications to these embodiments are contemplatedwithin the scope of the present application. Any alternatives ormodifications that make insubstantial changes in function, purpose,structure or result to the described embodiments are intended to beincluded within the scope of the invention as set forth in the claims.

Referring to FIG. 1, in one embodiment, an external bone fixation railsystem 10 includes a bone fusion tube or rail 12, at least one bracket14, and at least one ball collet assembly 15. Each ball collet assembly15 includes a collet clamp 16, an insert 32 disposed within collet clamp16, and a ball collet 18 (or simply “ball”) disposed within insert 32.Rail system 10 may also include one or more bone pins 20 for attachingsystem 10 to bone(s) B. In various embodiments, however, bone pins 20may be standard pins or rods used in a bone fixation procedure and mightnot be provided as part of system 10. Brackets 14 are attached to rail12, collet clamps 16 are attached to brackets 14, and bone pins 20 areinserted through ball collets 18.

A fastener 44 extends through each coupled pair of bracket 14 and colletclamp 16. When fastener 44 is relatively loose, its correspondingbracket 14 is free to slide along, and rotate around, rail 12. Whenfastener 44 is relatively loose, collet clamp 16 is also free to rotate,relative to bracket 14, and ball collect 18 is free to swivel and rotatewithin insert 32. In this way, the various parts of rail system 10 canmove about, relative to rail 12, to be able to attach to pins 20, whilefastener 44 is loose. When the various parts of system 10 are in desiredlocations relative to pins 20, each fastener 44 may then be tightened,which simultaneously (1) fixedly attaches bracket 14 to rail 12, (2)fixedly attaches collect clamp 16 to its respective bracket 14, and (3)compresses collet clamp 16, insert 32 and ball collet 18, to fixedlyhold onto pin 20. Thus, unlike any currently available or prior artexternal bone fixation system, adjustability and tightening of each setof components of external bone fixation rail system 10 is fullycontrolled by only one fastener. By this mechanism, rail system 10 isconfigured to connect rail 12 to multiple bone pins 20 connected to oneor more bones, often at different angles and orientations, for fixationand stabilization.

Rail 12 may be any size or shape, and rails 12 of many differing sizesand/or shapes may be included as part of rail system 10 or in multipledifferent embodiments of system 10. Rail 12 may, for example, have across-sectional shape that is circular, oblong, square, rectangular, orother shape, in various alternative embodiments. In the illustratedembodiment, rail 12 has a circular cross-section and a size designed forfixation of small bones, such as those of the foot or hand. For example,in embodiments of rail system 10 used for fixation of foot and anklebones, rail 12 may be provided in a relatively short length of betweenabout 2.25 inches and about 2.75 inches or a slightly longer length ofbetween about 3.75 inches and about 4.75 inches. Rail 12 is relativelyrigid and may be made of any suitable rigid material, such as but notlimited to stainless steel, carbon fiber, other rigid metals, highdensity plastic and other rigid polymers. When high density plastic isused, for example, rail may be radiolucent. Optionally, in someembodiments, rails 12 may have one or more recesses 22, detents 24 orcombinations thereof, which limit the axial sliding capability ofbrackets 14 mounted to rail 12.

Referring now to FIGS. 2A and 2B, ball collet 18 is illustrated ingreater detail. Ball collet 18 may be made of aluminum or a similarcrushable material, and it includes an aperture 26 for receiving bonepin 20. In various embodiments, aperture 26 may have any suitablediameter (e.g., 3 mm, 4 mm, 5 mm or 6 mm), to mate with a correspondingdiameter pin 20. Ball collet 18 further preferably includes a first pairof slits 28 (or “cuts”) and a second pair of slits 30. As can be seenfrom the side view of ball collet 18, in FIG. 2B, each pair of slits 28,30 extends approximately 90 percent along the length of ball collet 18,with each pair of perforations 28, 30 extending from opposite sides ofball collet 18. In other words, at one of aperture 26, only the firstpair of slits 28 will extend from the aperture through to the peripheryof ball collet 18, while at the other end of aperture 26, only thesecond pair of slits 30 will so extend. The fact that neither pair ofslits 28, 30 extends along the entire length of ball collet 18 may helpball collet 18 maintain its structural integrity when compressed bycollet clamp 16. At the same time, however, slits 28, 30 provide a“crush zone,” such that the application of a compressive force (asprovided and explained below) provides a friction fit between ballcollet 18 and pin 20. In alternative embodiments, ball collet 18 may bemade of different materials, have a different shape and/or have adifferent number and/or pattern of slits than in the embodiment of FIGS.2A and 2B. At least one alternative embodiment is described furtherbelow.

Referring now to FIG. 3, ball collet 18 may be supported by an insert 32(or “sleeve”), in some embodiments. In alternative embodiments, thefunction of insert 32 may be provided, instead, by a recess or grooveintegrally built into collet clamp 16. One advantage of insert 32 isthat the structure of collet clamp 16 and bracket 14 may be essentiallyidentical, thus allowing a modular, simpler manufacture and assembly ofthose two parts. Insert 32 may be made of any suitable plastic orsimilar material, such as polyether ether ketone (PEEK) plastic in oneembodiment. In the depicted embodiment, insert 32 is a PEEK plasticsleeve that includes a slit 34 and ridges 36. Slit 34 allows for easierplacement of ball collet 18 within insert 32 during assembly, and ridges36 help retain ball collet 18 within insert 32 once it is inserted. Ballcollet 18 is still free to rotate within insert 32 after placement andbefore collet clamp 16 is tightened by fastener 44. The ability of ballcollet 18 to freely rotate within insert 32 allows the surgeon or otheruser to easily adjust an angle of aperture 26 of ball collet 18 to fitover pin 20 at any of a variety of different angles.

Referring now to FIG. 4, ball collet assembly 15, bracket 14 andfastener 44 are illustrated in greater detail and coupled together. Ballcollet 18 resides within insert 32, and insert 32 resides within colletclamp 16. Collet clamp 16 and bracket 14 are coupled together viafastener 44 and may also be mated together via complementary colletclamp surface features 46 and bracket surface features 47. Bracket 14includes a main aperture 41, through which rail 12 slidably extends whenbracket 14 is attached to rail 12. Fastener 44 is a screw, in thisembodiment, but may be any of a number of different suitable fastenersin alternative embodiments.

Referring now to FIGS. 5A and 5B, side perspective views of bracket 14(FIG. 5A) and collet clamp 16 (FIG. 5B) are provided. Collet clamp 16includes a collet clamp support aperture 40, extending through the flatbottom of that component, and bracket 14 includes a bracket supportaperture 42. As mentioned above, in one embodiment bracket 14 and colletclamp 16 may have the same structure and thus be interchangeable. Forexample, if the image of bracket 14 in FIG. 5A were flipped to show theopposite side of bracket 14, it would look the same as collet clamp 16in FIG. 5B. In alternative embodiments, bracket 14 and collet clamp 16may have different structures. Also as mentioned above, bracket 14 andcollet clamp 16 may include complementary surface features (bracketsurface features 47 and collet clamp surface features 46) on theirsides, which mate with one another to provide a more firm and immovableconnection between bracket 14 and collet clamp 16 when fastener 44 istightened. When fastener 44 is loose, collet clamp 16 may be rotatedrelative to the bracket 14 around an axis defined by collet clampsupport aperture 40 and bracket support aperture 42.

In one embodiment, bracket support aperture 42 is threaded, and colletclamp support aperture 40 is not, to make threading fastener 44 throughcollet clamp 16 and bracket 14 easier. In alternative embodiments,bracket support aperture 42 and collet clamp support aperture 40 arethreaded, to provide truly identical structures for modular manufactureand assembly. Given the U-shaped structures of bracket 14 and colletclamp 16, tightening fastener 44 squeezes and provides a friction fitfor bracket 14 around rail 12, and prevents further movement of bracket14 along the length of rail 12. Tightening fastener 44 also squeezesbracket 14 and collet clamp 16 together, thus preventing furtherrotation of the two components relative to one another. Additionally,tightening fastener 44 squeezes the U-shaped bracket clamp 16, whichsqueezes insert 32 and ball collet 18, thus crimping/collapsing slits28, 30, which prevents further rotation of ball collet 18 in insert 32and firmly affixes ball collet 18 to pin 20. Therefore, tightening ofonly one, single fastener 44 secures each set of bracket 14 and ballcollet assembly 15 relative to one another, to rail 12 and to pin 20. Inother words, tightening one fastener 44 sets all of the different axesof rotation for one group of components on external fixation rail system10. This configuration is highly advantageous, in that it makestightening, loosening, repositioning and retightening each group ofcomponents very simple.

Referring now to FIGS. 6A-6D, another embodiment of an external bonefixation system 100 is illustrated. This embodiment of system 100 may beused for attaching to, and supporting, multiple bone pins in one or morefractured bones. Typically, system 100 is used for fractures of longbones in the lower limb, such as the femur, tibia and fibula. However,system 100 may also be used for long bones in the upper limb, and insome embodiments system 100 may be used for fixation of long bones andsmaller bones in the same limb, such as a long bone in the lower leg andone or more ankle and/or foot bones, in one example. Unlike rail system10 described above, external bone fixation system 100 is generallyconfigured to encircle a limb and thus provide surfaces for attaching tobone pins at locations around the circumference of the limb. (Similarcircumferential pin attachment may also be achieved using multiple railsystems 10 disposed around a circumference of an ankle or foot, forexample.)

In the illustrated embodiment, external bone fixation system 100includes a first semi-circular external fixation member 102, a secondsemi-circular external fixation member 104, four ball collet clampassemblies 106 attached to second external fixation member 104, and fourshafts 108. Each shaft 108 has a first end attached to first externalfixation member 102 via a shaft fastener 110 and a second end that has astop member 114 attached to it. Each shaft 108 passes slidably throughan opening in a ball 107 of one of the four ball collet assemblies 106attached to second external fixation member 104, and the stops 114prevent the second ends of shafts 108 from passing through the balls107. Each shaft 108 also includes a hinge 112, located closer to itsfirst end than to its second end.

First and second external fixation members 102, 104 include multipleattachment apertures 103, which may be used for attaching shaftfasteners 110, pin attachment devices (not illustrated) and/or ballcollet assemblies 106. Attachment apertures 103 also make first andsecond external fixation members 102, 104 lighter than they would bewithout apertures 103. In various embodiments, each of first and secondexternal fixation members 102, 104 may include any suitable number ofattachment apertures 103, such as but not limited to between four andforty attachment apertures 103, or more preferably between about twentyand thirty-five attachment apertures 103, and in one embodimentthirty-two attachment apertures 103. In the depicted embodiment, firstand second external fixation members 102, 104 both extend approximately270 degrees around a circle. When assembled within external bonefixation system first and second external fixation members 102, 104 maybe aligned such that their open portions face in opposite directions, asseen in FIGS. 6A-6D. Thus, together, first and second external fixationmembers 102, 104 may form a complete circle around a limb.

First and second external fixation members 102, 104 may have anysuitable size, and in various embodiments they may be provided in avariety of different sizes. In one embodiment, for example, first andsecond external fixation members 102, 104 may be sized such that adiameter measured across the circle that they form together isapproximately six and five-eighths inches. Alternative embodiments mayrange from as small as four inches in diameter or less to as many as teninches in diameter or more. As an optional feature, first externalfixation member 102 may include four lateral protrusions 105 orprojections, each of which includes one attachment aperture 103, towhich one of shaft fasteners 110 is attached. In other embodiments, bothfirst and second external fixation members 102, 104 may include suchlateral protrusions 105, or alternatively neither of them may includelateral protrusions 105. First and second external fixation members 102,104 may be made out of any suitable metal or polymer, as long as it issufficiently strong and rigid to provide stable attachment and supportof bone pins. In some embodiments, the outer surface of first and secondexternal fixation members 102, 104 may be rough, from a coating on, or atreatment of, the external surface. The rough outer surface may helpfacilitate attachment of bone pin attachment devices to first and secondexternal fixation members 102, 104.

Shaft fasteners 110 may include two bolts and a dowel, with the dowelrunning through one of attachment apertures 103. In some embodiments,shaft fasteners 110 are free to spin or rotate within their attachmentapertures 103, thus allowing shafts 108 to spin, relative to firstexternal fixation member 102. As mentioned above, each shaft 108 alsoincludes hinge 112. Together, the spinning of shaft fasteners 110 andthe bending of hinges 112 allows system 100 as a whole to twist. Hinges112 also allow system 100 to fully collapse from an extended or expandedconfiguration, as illustrated in FIGS. 6A and 6B, to a fully collapsedconfiguration, as illustrated in FIG. 6D. In the fully extendedconfiguration, second external fixation member 104 contacts stops 114.In the fully collapsed configuration, second external fixation member104 is located between hinges 112 and first external fixation member102, thus allowing hinges 112 to be fully bent. This fully collapsedconfiguration may be highly advantageous for packaging, transport andstorage of system 100. Just as first and second external fixationmembers 102, 104 may be made of any suitable metal or polymer, so toomay shafts 108, hinges 112, shaft fasteners 110 and stops 114 be made ofany suitable metal, polymer or combination thereof. In one embodiment,for example, all components of system 100 may be made of metal. In otherembodiments, most of the components may be metal, with one or more othercomponents being made of a polymer, such as stops 114 and/or one or moreparts of ball collet assemblies 106. In one embodiment, stops 114 arecircumferential of rubber parts that are attached to the second ends ofshafts 108 and are wider than the outer circumference of the shafts 108.Alternatively, however, stops 114 may be formed as an integral part ofshafts 108 (in other words, each shaft 108 and stop 114 is one piece),and shafts 114 may be made of the same material as shafts 108.

Shafts 108 may have any suitable dimensions and configurations. In oneembodiment, for example, one shaft 108 may have a length, not includingstop 114 or a hinge portion of shaft 108, of about seven andseven-eighths inches. Including the hinge portion, shaft 108 may have alength of about eight and five-eighths inches. The same embodiment ofshaft 108 may have a diameter of about one half inch. Each shaft 108 maybe a single piece or multiple pieces, in various embodiments. Forexample, in one embodiment, each shaft 108 may include a separate hingeportion, which may be attached to the first end of shaft 108. Inalternative embodiments, each shaft 108 may include an integral hingeportion. Shafts 108 may be made of stainless steel, aluminum, titanium,or any other suitable metal or polymer.

In use, external bone fixation system 100 may first be extended from itscollapsed configuration (such as in a package) to its fully extended(FIG. 6A) or partially extended (FIG. 6C) configuration. System 100 maythen be positioned around a patient's lower limb (or alternatively anupper limb) by positioning first and second external fixation members102, 104 around the limb. Alternatively, first and second externalfixation members 102, 104 may be passed over the limb with system 100 inthe collapsed configuration, and then system 100 may be expanded. Thepositions of first and second external fixation members 102, 104 may beadjusted, according to the desire of the physician, to allow the bestpositioning relative to any bone pins to be attached to system 100. Whena desired positioning is achieved, ball collet assemblies 106 may betightened, to lock second external fixation member 104 rigidly andimmovably to shafts 108. At this point, system 100 may be attached toany number of bone pins extending out of the patient's bone(s), usingany number of bone pin attachment devices, which are not illustratedhere. These bone pin attachment devices may be any currently availableor future bone pin attachment devices, and they may be provided as partof system 100 or provided separately, in various embodiments. The bonepin attachment devices attach, in some embodiments, to attachmentapertures of first and second external fixation members 102, 104. Theadjustability of system 100 provided by ball collet assemblies 106,hinges 112 and spinning shaft fasteners 110 is believed to be highlyadvantageous to users and a significant improvement over currentlyavailable external bone fixation systems.

With reference now to FIG. 7, ball collet assembly 106 of external bonefixation system 100 is illustrated in greater detail. In thisembodiment, ball collet assembly 106 includes a metallic ball 107,fitted inside an insert 118, which in turn is fitted inside a colletclamp 116. Ball 107 includes two slits 120 a, 120 b and a central ballopening 122. In this embodiment, a first slit 120 a is cut all the waythrough the full thickness of ball 107 (from central ball opening 122 tothe ball's outer surface), along its entire length, and a second slit120 b extends through the full thickness of ball 107 only on the twoends of second slit 120 b. A middle portion of second slit 120 b is onlyon the inside surface of ball 107 (starting from central ball opening122 but not extending to the ball's outer surface). When compressingpressure is exerted on ball 107, via collet clamp 116 and insert 118,slits 120 a, 120 b allow ball 107 to partially collapse, and thustightly hold onto one of shafts 108, while still maintaining its generalspherical shape and structural integrity. In some embodiments, ball 107may be made of aluminum and may have a rough textured outer surface,which may enhance the ability of ball 107 to adhere to the inner surfaceof insert 118. Ball 107 may have any suitable size, such as aboutthirteen-sixteenths of an inch in one embodiment, or between half aninch and one inch in various alternative embodiments.

Insert 118 may be made of a polymeric material, such as PEEK plastic inone embodiment, and may include a central insert opening 124 and one ormore slits 126. In alternative embodiments, insert 118 may be made of adifferent material, such as metal, or may be eliminated from ball colletassembly 106 completely. In embodiments without insert 118, collet clamp116 may include an inner surface, forming an inner clamp opening 132,which has one or more features (such as outer rims, texture, etc.) toreplicate insert 118. In the embodiment illustrated, however, insert 118fits within inner clamp opening 132 and is configured to partiallycollapse around ball 107 when compressive force is exerted upon it bycollet clamp 116. Insert 118 may include outer rims on the edges of itsinner surface, in order to better hold onto ball 107.

Collet clamp 116 may be made of aluminum, another metal, PEEK plastic,or another polymeric material. Collet clamp 116 may extend around mostof a complete circumference of inner clamp opening 132, but may includea slit 134 to allow inner clamp opening 132 to shrink when collet clamp116 is tightened. Collet clamp 116 typically includes at least oneattachment aperture 128, for passage of an attachment fastener 137 (notshown in FIG. 7, see FIGS. 6A-6D), for attaching clamp 116 to secondexternal fixation member 104, and a cutout portion 138 for allowingcollet clamp 116 to fit over second external fixation member 104.Attachment fastener 137 may be a bolt and a nut, for example, oralternatively any other suitable fastening device. Collet clamp 116 alsotypically includes a tightening aperture 130, for passage of atightening fastener 136 for tightening clamp. Tightening fastener 136may be a bolt, a screw or the like, in one embodiment, and tighteningaperture 130 may include threads on part or all of its surface, formating with tightening fastener 136 and allowing collet clamp 116 to betightened. In some embodiments, Helicoil may be added to the threadedportion of tightening aperture 130, to add strength to the connectionbetween tightening fastener 136 and the threads. Additionally, thethreads of tightening fastener 136 may be coated with Teflon forsmoother tightening action and to facilitate tightening and looseningtightening fastener 136 multiple times.

Referring now to FIG. 8, in some embodiments, external bone fixationsystem 100 may be used with additional systems or with add-on sets ofcomponents. For example, as illustrated, a first set of add-on externalbone fixation components 200 may be attached to a proximal end of system100, and a second set of add-on external bone fixation components 220may be attached to a distal end of system 100. These add-ons allowsystem 100 to be extended to cover a longer length of a lower limb L (orupper limb in alternative embodiments). Any given set of components,such as first set 200, may include any suitable combination of any ofthe components described above, as well as any variations on suchcomponents (different sizes, configurations, numbers of components,materials, etc.). In the illustrated embodiment, for example, first set200 includes an additional external fixation member 202, multipleadditional shafts 208 and multiple additional ball collet assemblies206. FIG. 8 also illustrates one bone pin 140, as is typicallyattachable to one of the external fixation members 102, 104, 202. Theembodiment illustrated in FIG. 8 is only one example of how system 100may be combined with additional sets of components, 200, 220. Inalternative embodiments, any suitable number, combination andconfiguration of additional components may be combined with system 100for use on a given patient.

With reference to FIG. 9, another embodiment of an external bonefixation system 300 (or a set of add-on components for system 100) isillustrated. In this embodiment, system 300 includes a first externalfixation member 302 and a second external fixation member 304, both ofwhich are structurally the same and include lateral protrusions 305 andmultiple attachment apertures 303. Four ball collet assemblies 106 areattached at four different locations on attachment apertures 303 onlateral protrusions 305. Ball collet assemblies 106 may be the same,similar or differently structured, as compared to previously describedembodiments. Shafts 308 connect the first and second external fixationmembers 302, 304 together, via ball collet assemblies. In thisembodiment, shafts 308 are significantly shorter than shafts 108described previously. Thus, system 300 may be useful for covering ashorter portion of a body, such as a foot/ankle portion or a hand/wristportion of a body. This embodiment also differs from those previouslydescribed in that two of ball collet assemblies 106 are attached tosecond external fixation member 304 via a post fastener 337. In someembodiments, post fastener 337 may be free to rotate within itsattachment aperture 303, while in alternative embodiments it may rigidlyfix ball collet assembly to second external fixation member 304. Ineither case, post fastener 337 allows first and second external fixationmembers 302, 304 to be aligned at right angles or other angles, relativeto one another. This may be especially useful for attaching system 300to bones in and around an ankle, for example. Again, external bonefixation system 300 is merely one example of a combination of componentsdescribed herein for external bone fixation.

The above description is not intended to limit the scope of thefollowing claims. Rather, modifications in structure, function or resultare intended to be covered by the claims. Various changes, additions,omissions, and modifications can be made to the illustrated embodiments,without departing from the spirit of the present invention. All suchmodifications and changes are intended to be covered by the followingclaims.

1. (canceled)
 2. An external bone fixation system, comprising: a firstexternal fixation member; a second external fixation member; a firstshaft; a second shaft; and four ball collets, wherein each of the fourball collets is attached to one end of one of the first shaft or thesecond shaft, so that each end of the first shaft and the second shafthas one of the four ball collets attached to it, wherein the firstexternal fixation member is attached to the first shaft and the secondshaft via two of the four ball collets, and wherein the second externalfixation member is attached to the first shaft and the second shaft viathe two other of the four ball collets.
 3. The external bone fixationsystem of claim 2, wherein each of the first shaft and the second shaftcomprises: a first end attached to the first external fixation membervia one of the four ball collets; and a second end attached to thesecond external fixation member via one of the four ball collets.
 4. Theexternal bone fixation system of claim 3, wherein the first externalfixation member is slidable along the first shaft and the second shaft,toward the second external fixation member.
 5. The system of claim 1,wherein each of the four ball collets comprises: a ball; and a clampconfigured to fit over the ball.
 6. The system of claim 5, wherein thefirst external fixation member is coupled with two of the clamps, whichare attached to two balls of two ball collets, and wherein the secondexternal fixation member is coupled with two others of the clamps, whichare attached to two balls of two ball collets.
 7. The system of claim 6,wherein each of the first external fixation member and the secondexternal fixation member comprises multiple apertures for holding bonepins.
 8. The system of claim 5, wherein the ball comprises a roughenedsurface.
 9. The system of claim 5, wherein the ball comprises multiplelongitudinal slits.
 10. The system of claim 5, wherein the ballcomprises aluminum with a rough surface coating.
 11. The system of claim5, wherein the ball comprises: at least one full thickness, full lengthslit, extending from one end of the ball to an opposite end and from thecentral opening to an outer surface of the ball; and at least onepartial slit, comprising: a full thickness portion extending from thecentral opening to the outer surface; and a partial thickness portionextending only partway from the central opening to the outer surface.12. The system of claim 11, wherein the full thickness portion comprisestwo lengths of the partial slit, located at opposite ends of the centralopening, and wherein the partial thickness portion is located betweenthe two lengths of the full thickness portion.
 13. The system of claim5, wherein the clamp comprises a threaded aperture for accepting a screwto tighten the clamp, and wherein a surface of the threaded aperture iscoated with Teflon.
 14. The system of claim 1, wherein the first shaftis parallel to the second shaft.